1. Field of the Invention
The present invention relates to automatic discrimination of a disk-shaped information storage medium, and more particularly to a method and apparatus capable of identifying different types of disk-shaped information storage media, each having a diameter different from each other.
2. Description of the Related Art
Referring to FIG. 1, a driving/detection apparatus in a conventional disk-shaped information storage medium reproduction apparatus comprises a pickup 11 for reading out information recorded in a disk-shaped information storage medium 10 by using a laser beam irradiated by an LED; a sled motor 12a for moving the pickup 11 in the radial direction of the disk-shaped information storage medium 10; a spindle motor 12b for rotating the disk-shaped information storage medium 10; a driving unit 30 for driving the sled motor 12a and the spindle motor 12b; an RF (radio-frequency) signal processing unit 20 for amplifying and filtering signals picked up by the pickup 11; a servo control unit 40 for servo-controlling the driving unit 30 on the basis of a focus error signal, tracking error signal, and the rotational speed of the disk-shaped information storage medium 10 and for detecting synchronization codes from the output of the RF signal processing unit 20; a digital signal processing unit (DSP) 50 for converting analog signals from the RF signal processing unit 20 received through servo control unit 40 into digital signals; a memory 70 for storing the time it takes for a GFS (Good Frame Sync.) signal from DSP 50 to be detected since the initial rotation of the disk-shaped information storage medium 10, so-called GFS detection time; a timer 80 for counting the time elapsed since the initial rotation; a MICOM (microcomputer) 60 for controlling the overall operations of the above-described components.
In the driving/detection apparatus configured as above, the conventional method for detecting the size of a disk-shaped information storage medium is as follows. Once a disk-shaped information storage medium is loaded, the driving/detection apparatus is initialized and then the disk-shaped information storage medium is rotated by the spindle motor 12b, which is driven by the servo control unit 40 and the driving unit 30 responsive to the MICOM 60. A voltage level applied to the spindle motor 12b is determined such that the initial over-rotation of the disk-shaped information storage medium does not occur. Specifically, a voltage level which is adequate to rotate the lightest disk-shaped information storage medium, or a disk having a diameter of 8 cm at a stable speed, is supplied to the sled motor 12b. Under control of the MICOM 60, data on the disk-shaped information storage medium 10 is read out while the pickup 11 travels along the tracks of the disk-shaped information storage medium, and at the same time, the timer 80 starts to count the present time.
The analog signal read out by the pickup 11 is filtered by the RF signal processing unit 20. And then, with reference to a synchronous signal detected by the servo control unit 40, digital data is obtained from the analog signal by the digital signal processing unit (xe2x80x9cDSPxe2x80x9d) 50.
At that time, the digital, data is obtained in the unit of frame, which is made up of 588 bits, as shown in FIG. 2. Once the rotational speed of the disk-shaped information storage medium 10 becomes equal to a preset desired speed, synchronization codes of 24 bits are read out periodically. When eight (8) synchronization codes are consecutively readout, the digital signal processing unit 50 sends a GFS signal to the MICOM 60, which stop the timer""s count operation of the current time.
On receiving the GFS signal, the MICOM 60 reads the time T elapsed before the reception of the GFS signal from the timer 80. In order to determine the size of the disk-shaped information storage medium, the elapsed time T is compared, in a predetermined tolerance range, to three reference times (Ta, Tb, Tc) which represent three GFS detection times respectively corresponding to three differently sized optical discs having diameters of 8 cm, 10 cm, and 12 cm, as shown in FIG. 3. The three reference GFS detection times are stored in the memory 70.
However, in order to identify the types of disk-shaped information storage media according to their sizes, the conventional method requires the time duration it takes for the rotational speed of a disk-shaped information storage medium to reach a constant linear velocity because GFS signals are obtainable only during stable rotation.
Moreover, a driving unit must be controlled carefully enough to drive the disk-shaped information storage medium stabily, regardless of its diameter. Because it takes longer to achieve stable driving of disk-shaped information storage mediums having greater diameters, the GFS detection times of disk-shaped information storage media having diameters larger than 8 cm are much longer than that of disk-shaped information storage medium having a diameter of 8 cm or less.
The present invention is directed to a system and method that substantially obviates one or more of the problems experienced due to the above and other limitations and disadvantages of the related art.
It is an object of the present invention to provide a method and apparatus which enables identification of different types of disk-shaped information storage media, each having a diameter different from each other, in a shorter period of time.
Other and further objects, features and advantages of the present invention will be set forth in the description that follows, and in part will become apparent from the detailed description, or may be learned by practice of the invention.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention includes an apparatus for automatically identifying the types of disk-shaped information storage media according to their sizes, comprising means for detecting a signal produced from a driving means for rotating a disk-shaped information storage medium; a timer for counting the time elapsed since the signal from the driving means begins to be detected; means for comparing either the signal generated from the detecting means or the elapsed time produced from the timer with the corresponding reference signal or time duration; and means for identifying the type of the disk-shaped information storage medium according to the size thereof on the basis of the comparison result.
In a method for identifying the types of disk-shaped information storage media according to the present invention, once a disk-shaped information storage medium is loaded in a disk driver, the disk-shaped information storage medium is rotated by a predetermined driving force. Signals are detected that are generated in proportion to the rotational amount, and at the same time, the time elapsed since the detection of the signals is counted. By using the detected signals and the elapsed time, the size of the disk-shaped information storage medium is detected and used to identify the type thereof.
According to the apparatus and method of the present invention, once a disk-shaped information storage medium is loaded in a disk driver, the information storage medium is rotated by a predetermined driving force. The signal detection means detects signal that is generated in proportion to the rotational amount, and at the same time, the timer counts the time elapsed since the signals begin to be detected. A comparison is made, in the determination means, as to whether the elapsed time corresponds to a reference time duration or the number of pulses in the detected signal is equal to a reference number of pulses. Based on the comparison result, the size of the disk-shaped information storage medium is detected, and thus the type thereof is identified.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Thus, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of example only. Various changes and modifications that are within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In fact, other objects, features and characteristics of the present invention; methods, operation, and functions of the related elements of the structure; combinations of parts; and economies of manufacture will surely become apparent from the following detailed description of the preferred embodiments and accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in various figures.